This invention relates to a method of welding tubes to a tube sheet of a heat exchanger and more particularly to a method of continuously welding tubes in a plurality of rows utilizing a continuous weld. When tubes are individually welded to a tube sheet the shielding gas must be turned on to purge the weld area; the arc must be initiated; the weld made and the power to the arc ramped down to prevent cracking in the weld and the shield gas must be supplied as the well puddle solidifies. On the other hand, if a continuous weld is made encompassing a plurality of tubes several of the steps mentioned above need only be performed once for the entire weld cycle thus reducing the overall welding time by a factor in the neighborhood of 2 to 4. The continuous weld also has the advantage of improving the overall quality of the welds as defects are more apt to occur at the initiation and extinguishing of the arc.
An obstruction to continuous welds is that tubes are not disposed on exactly even pitches so that predetermined paths with no compensation for the exact location of each tube will not produce acceptable welds.